Brewster High School freshman Pete Ivey (Dolley) is introverted and socially awkward, but his best friend Cleatus Poole (Musso) is the school mascot, the Chicken. At a basketball pep rally, Pete tries to ask out super hot cheerleading captain and Cleatus' sister Camie (Thornton), before learning she's dating team captain Dill when he interrupts them. However, when Cleatus asks Pete to fill in the mascot position due to his suit allergies catching up with him, Pete is hesitant at first, but realizes it could be an opportunity to have fun and change his fortunes with girls. Following an out-there performance at the next game, Cleatus starts to get adoration from students but ire from Coach Mackey and teachers. He convinces Pete to be the Chicken full-time. After having done so for a while, Pete must eventually decide whether to stay hidden and let Cleatus keep getting the credit or reveal himself to potentially gain his long sought after and well-deserved popularity.
Hatching Pete provides examples of these tropes:
- Alpha Bitch: Downplayed. Camie is a little bitchy towards her fellow cheerleaders, but mostly nice towards everyone else.
- Down to the Last Play: Dill makes a buzzer beater and scores the winning 3-point shot.
- "Get Out of Jail Free" Card: The principal convinces the sheriff to drop charges on the Chicken for stealing the latter's car because they need the Chicken to lift up the team's spirits. Cleatus even lampshades that.
- No Social Skills: Pete has always had trouble talking to anyone that's not Cleatus or his family.
- Paper-Thin Disguise: It's a wonder how no one notices Cleatus in his Cowboy disguise during the parade until his fake mustache partially slips off.
- Pompom Girl: As the Chicken, Pete gets used into cheering up the team with the cheerleaders, but only two have names: Camie, who starting dating Cleatus only because she thinks he is the chicken, and Angela, who is honest, kind and very mature for a teenager. Of course Pete falls for the latter.
- Underdogs Never Lose: Averted throughout most of the movie; the Brewster Roosters haven't won a single game in years and never get a win throughout the movie season as well. Played straight in the final game, though, where they win at the last second.
- "Well Done, Son" Guy: Even though Cleatus hates being the chicken, mostly because he is allergic to the suit, he refuses to quit because he has family legacy to live up to, as his family members, including his father and grandfather, were the chicken before him. After Pete becomes a hit with the crowd as the chicken, Cleatus' dad, Jack, wants to spend time with him, but Cleatus feels upset because he thinks his dad only loves him for being a great mascot, but Pete assures him his dad loves him no matter what. After Cleatus is finally ousted to not being the Chicken, he admits the truth to how he was allergic and suffering to Jack, who reveals he was allergic to the suit too, but he didn't have to guts to quit. Jack then says he's of proud of Cleatus for finding a way to get out his situation, and tells him he would rather him be his happy son than suffering as the chicken.